1. Field of the Invention
The present invention relates to a method for switching connections between two connection systems, and in particular to connection systems each having a transmitting channel and a receiving channel.
The use of telecommunication services for transmitting speech and data is continuously increasing due to an increasing global orientation of companies.
2. Description of the Related Art
As such the costs caused by these telecommunication services are continuously increasing and become a considerable cost factor for the companies, which search for possibilities in order to reduce these costs. Global computer networks such as the xe2x80x9cinternetxe2x80x9d offer one possibility for cost-efficiently transmitting data worldwide.
The United States patent application having the official Ser. No. 08/942,592 has already proposed a method for enabling a transmission of data to be transmitted in the framework of a speech connection via a computer network such as the xe2x80x9cinternetxe2x80x9d. It has also been proposed that a new connection is set up via an alternative communication networkxe2x80x94for example an ISDN-oriented communication network (Integrated Services Digital Network) when a sufficient transmission quality can be no longer assured in the framework of a realtime-critical transmission of speech data via the computer network and that the data to be transmitted are then transmitted via this new connection.
The present invention is based on the object of providing a method for establishing a new connection via a telecommunication network, whereby the interrupt time for switching from a previous connection led via a computer network to the new connection led via a telecommunication network can be minimized.
According to principles of the related art, if a first communication system, which, on one hand, is connected to a telecommunication network such as the ISDN communication network and, on the other hand, to the internet via a first internet terminal unitxe2x80x94frequently abbreviated as TIS (Telephony Internet Server) in the literaturexe2x80x94receives a call number identifying a called terminal device from a calling terminal device, it is checked whether the received call number or, portions of the received call number identifying the target are entered into a list that is stored in the communication system. This list contains bits of routing information allocated to the call numbers or, to the portions of these call numbers identifying the target, whereby said bits of routing information disclose that a connection for transmitting speech data has already been set up via the xe2x80x9cinternetxe2x80x9d.
If the received call number or, portions of the received call number identifying the target is not deposited in the list, the first communication system sends a signaling message via the telecommunication network to a second communication system, which has the called terminal device allocated. This signaling message signalizes with respect to the second communication system that the first communication system is connected via a first internet terminal unit to the xe2x80x9cinternetxe2x80x9d. If the second communication system is also connected via a second internet terminal unit to the xe2x80x9cinternetxe2x80x9d, the second communication system signalizes this with respect to the first communication system together with the internet address of the second internet terminal unit in a corresponding response message.
If the first communication system does not receive a response message within an adjustable time interval, the connection between the calling terminal device and the called terminal device is traditionally set up via the telecommunication network.
If the call number or, the portions of the received call number identifying the target received at the first communication system is entered into the list, or when the first communication system receives a response message within the adjustable time interval, the fist communication system transmits the internet address of the second internet terminal unit to the first internet terminal unit. If the transmission bandwidth provided via the internet connection between the first internet terminal unit and the second internet terminal unit is sufficient for a realtime-critical transmission of speech data, the fist internet terminal unit packages the speech data, which are transmitted by the calling terminal device and which are potentially digitalized in the first communication system, into data packets according to the IP protocol (Internet Protocol) and transmits them to the second internet terminal unit on the basis of the internet address of the second internet terminal unit. The second internet terminal unit unpacks the speech data contained in the transmitted data packets, transforms them into a time slot-oriented data format (TDM: Time Division Multiplex) provided for the further transport, and forwards them via the second communication system to the called terminal device. The speech data are transmitted from the called terminal device to the calling terminal device in a corresponding manner.
If the first communication system or, the first internet terminal unit finds out during the call that the transmission qualityxe2x80x94frequently also referred to as xe2x80x9cQuality of Service QoSxe2x80x9d in the literaturexe2x80x94of the internet connection between the first and the second internet terminal unit is no longer sufficient for the realtime-critical transmission of speech data in the framework of the call between the calling terminal device and the called terminal device, a new connection, proceeding from the first communication system, is normally set up via the telecommunication network to the second communication system and the data transmission is subsequently reconnected onto this new connection. Alternatively, the transmission quality of the internet connection between the first and the second internet terminal unit can also be monitored by the second communication system or, the second internet terminal unit.
A bidirectional data transmission between the first and the second communication system is generally possible via both connections. For this purpose, both bidirectional connections consist of two unidirectional connections via which the communication systems that are a part of the connection respectively transmit data or, receive data. These two unidirectional connections are generally referred to as transmission path and as reception path.
Given a reconnecting of the existing connection onto the new connection in the traditional way, whereby a simultaneous switching of the transmission path and of the reception path occurs on the calling part and also on the called part, longer interrupt times arise by message runtimes of the messages to be transmitted between the involved communication systems for the reconnecting, whereby data cannot be transmitted in said interrupt times. Given a specific number of network nodes to be passed, these interrupt times can be within a second range in larger telecommunication networks and therefore are not acceptable.
The present invention discloses a method that reduces these interrupt times by controlling the communication systems as to the transmission/reception paths of the network.
A critical advantage of the inventive method is that the method can be simply implemented in already existing systems.
Furthermore, the present may be implemented upon a decline of the transmission quality beyond a predetermined value. This predetermined value may be provided by one of the communication networks.